Cognitive Changes Caused by Cancer and Cancer Treatment

Cancer and/or cancer treatment may cause changes in cognition, such as difficulty concentrating, mental slowing, memory loss, problems understanding or problems organizing thoughts. Cognitive problems are also referred to as cognitive deficits or cognitive dysfunction. 

Behavioral and emotional problems related to cancer and/or cancer treatment may include anxiety, depression, irritability, mood swings, and changes in personality, such as irrational behavior or inappropriate social behavior. 

In terms of cancer, cognitive, behavioral and emotional changes may be caused by:

Brain Tumors

Each year, more than 200,000 people in the United States are diagnosed with a brain tumor. As a tumor grows in the brain, it places increased pressure on surrounding tissue and destroys healthy brain cells, which can cause cognitive and emotional changes. 

It is estimated that approximately 50 to 80 percent of people diagnosed with a brain tumor experience changes in cognition and behavior at the time of diagnosis. The size, type and location of the tumor all play a role in determining whether a person will experience cognitive problems and what form they will take.

With a limited amount of space in the skull, the growth of a tumor can damage brain tissue and change the way the brain works. Brain tumors can also destroy healthy tissue as it grows. Any cognitive and/or behavioral changes that occur depend on the size, type and location of the tumor. 

These changes may be temporary and go away over time, or improve with treatment. Cognitive changes can also be longstanding and in some cases permanent. Whether cognitive changes will improve depends largely on their cause.

Chemotherapy Can Affect Healthy Cells

Chemotherapy is used to treat a wide range of cancers and has been shown to be effective in killing cancer cells; however, chemotherapy can also damage healthy cells. Chemotherapy is a systemic treatment, which means it goes through the entire body and affects every cell. 

Therefore, chemotherapy will reach brain cells. Chemotherapy is also used to directly treat certain types of brain tumors often in combination with radiation therapy. Increasing evidence suggests that chemotherapy affects the brain and central nervous system. The damage, which may be temporary, depends on the type of chemotherapy used, how long it is given, and whether it is combined with other forms of treatment. 

It is estimated that at least 30 percent of women who receive chemotherapy to treat breast cancer experience cognitive changes during and, in some cases, for some time after chemotherapy. Chemotherapy for other types of cancers can also affect cognition. The effect of chemotherapy on the brain is sometimes referred to as “chemobrain,” “chemohead” or “chemofog.”

Radiation Therapy Can Damage Healthy Tissue

Radiation therapy may be used when surgery is not possible, for tumors that cannot be completely removed, or after surgery to prevent or delay the tumor from recurring. While radiation to the brain can kill cancer cells, it can also damage healthy tissue near the tumor. 

Radiation therapy to the brain may damage the “white matter” tracts in our brain, which are very important for rapid communication between brain regions, as well as affect blood vessels in our brain. These changes can cause cognitive symptoms as well.  Some patients who undergo brain radiation develop cognitive symptoms. The extent and degree of cognitive change depends on how much surrounding healthy tissue is damaged from the radiation. 

Brain Surgery Can Decline Cognition

Brain surgery is performed to remove cancerous cells or tumors from the brain. In some cases, removal or partial removal of a brain tumor can lead to improvements in cognition by lowering the pressure exerted on the brain by the tumor and reducing brain swelling. Brain surgery can also cause declines in cognition due to removal of healthy tissue when removing the tumor. The level of cognitive change depends on the amount of damage to surrounding healthy tissue during surgery.

Additional Treatment Causing Cognitive Changes

  • Certain medications used to treat symptoms associated with cancer.
  • Medical complications such as seizures, anemia and endocrine dysfunction.
  • Psychological distress associated with having cancer and undergoing cancer treatments.
  • Physical symptoms such as fatigue and pain.

Cognitive and other changes are often subtle, and not all patients will experience these problems. For those who do, cognitive problems may range from mild to severe, and they may be temporary or persist long after treatment has ended. Cognitive changes can happen suddenly, or they can develop slowly over time.

Cognitive changes can affect many parts of a person’s life, such as the ability to work, socialize or do everyday tasks. The sooner cognitive changes are discovered, the sooner steps can be taken to treat the problems and optimize a person’s cognitive function and quality of life. 

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